Question

Name a gas that can act as an oxidizing as well as a reducing agent:

• A. Chlorine
• B. Oxygen
• C. Hydrogen
• D. Nitrogen

Answer 1

Answer: (A), (B), (C), (D)

The correct options are
A Chlorine
B Oxygen
C Hydrogen
D Nitrogen

One example is hydrogen gas, which acts as an oxidizing agent when it combines with metals and as a reducing agent when it reacts with nonmetals. Another example is hydrogen peroxide, in which the oxygen atom is in the -1 oxidation state.
Hydrogen peroxide, $H_2{O}_2$:
In this molecule the oxidation number for oxygen is 1. This is halfway between $O_2\left(0\right)$ and $H_{2}O\left(2\right)$, and so hydrogen peroxide can either be reduced or oxidized. When it is reduced, it acts as an oxidizing agent:
$H_2{O}_2+2H^{+}+2e^{\to }2H_{2}O$
When it is oxidized, it serves as a reducing agent:
$H_2{O}_2$ gives $O_2$+ 2$H^{+}$+ 2e
Hydrogen peroxide is considerably stronger as an oxidizing agent than as a reducing agent, especially in acidic solutions.